The San Cristobal Wash is an ephemeral wash and watercourse of the San Cristobal Valley, flowing north into the Gila River Valley of the southwestern desert region of Arizona.
The wash ends its watercourse one third of the way into the valley, and disappears about 8 miles (13 km) south of the Gila River.
The majority of the wash lies in the southeast of Yuma County, but southeast drainages from the Growler Valley area drain extreme western Pima County.
Southern portions of the San Cristobal Wash extend to the southern ends of two valleys and the drainage bifurcates, draining the Mohawk Valley southeasterly on the west and the southern-(south-flowing into headwaters of San Cristobal Wash), Growler Valley, on the east.
Drainages going northwest combine from the southeast into the San Cristobal Wash: the Growler Wash from the Growler Valley east of the Granite Mountains (Arizona), and east of there the Daniels Arroyo, which flows adjacent to the Tenmile Wash Drainage in the Childs Valley of southern Arizona, Pima County.